A 10-year-old boy with immobilization shows signs of muscle atrophy. What change in capillarity is expected in the immobilized muscle?

• A. Increased vascularization
• B. No change
• C. Decreased capillarity
• D. Increased oxygen saturation

Answer: (C)

In cases of immobilization, muscle tissues undergo adaptations due to reduced mechanical loading. One significant change that occurs in immobilized muscle is decreased capillarity, which is the reduction in the density of blood vessels supplying the muscle. This decrease in vascularization directly relates to the muscle atrophy seen in immobilization.

When muscles are not actively used, there is a diminished demand for oxygen and nutrients, leading the body to reduce the number of capillaries. As the muscle fibers atrophy, the metabolic needs of the muscle decrease, resulting in fewer capillary networks being maintained. This is a response to preserve energy and resources because the workload on the muscle is significantly reduced. Thus, the correct response reflects the physiological changes in the muscle as it adapts to the lack of movement and activity.